The present invention is a distinctive improvement over that sewing system shown in U.S. patent application, Ser. No. 319,671 filed Nov. 9, 1981, now U.S. Pat. No. 4,428,315.
Like the present invention, the above-identified application discloses a method and apparatus for automatically forming a shirt sleeve from a sleeve blank. One of the most important and demanding steps in the disclosed automated system concerns the transference of the workpiece from one conveyor to another. To assure proper sleeve formation after transference, the overlapping edges of the workpiece should be substantially aligned. If the edges are not substantially aligned, any or all of the following problems may result. First, the seaming of the edges may not properly be effected. Alternatively, if the overlapping edges of the folded blank are not properly aligned the resultant mismatched product could present severe problems on subsequent insertion operations. Moreover, if the edges of the folded over blank are not properly aligned, the resultant sleeve size may alter considerably from that which is desired.
The apparatus disclosed in the above-identified application does not provide adequate measures whereby those problems are obviated. Instead, the disclosed automatic apparatus utilizes a single sensor for controlling the pick up head as a function of the initial advancing edge detection. The mere detection of the leading edge will not, however, serve to avoid the problems.
A preset sensor assumes that neither the workpiece size nor the advancement rate of the workpiece will vary during sewing. As a skilled artesian may well appreciate, however, such assumptions are unfounded. Workpiece sizes may vary considerably in length. Moreover, the advance rate of the workpiece may also be readily changed to enhance production schedules. In short, the provision of a single edge detection system for activating the pick up arm to effect workpiece transference will not assure that the workpiece will be folded in half. Accordingly, mismatching of the overlapping edges may well result.